In metal stamping plants, such as engaged in forming body components for the automotive industry, flat sheet metal blanks must be cleaned and treated with a liquid drawing compound preparatory to the forming operations. In conventional practice, a stack of blanks, which may have been sheared or die cut to irregular shapes preparatory to forming, are automatically fed through a washing station in which rotary brushes are supplied through tubular hubs with a fluid cleaning and drawing compound and distributed by the brushes to the passing surfaces of the blank. Wringer rollers are employed to drive the blanks and retain the liquid within the station and meter such liquid for drawing purposes.
Surplus drawing compound flowing off the surface of the blanks is collected in a tank under the brushes and recycled through filters before return to the brushes. Such operations are subject to certain problems: Blank edge engagement of the brush bristles may include irregular burrs tending to cut or pull the bristles loose. They may adhere, on occasion, to the surface of the blanks admitted to the forming press where they may be pressed into the surface creating imperfections, particularly objectionable in light gauge sheet metal of which current automotive bodies are formed. In addition, grit and debris on the blank surfaces accummulated from preceding operations are not always effectively removed by the brush action, particularly as the brushes accumulate deposits picked up from the blank surfaces. Furthermore, the brushes and wringer rollers are subject to rapid wear and attrition involving the expense of frequent shut down and replacement.